Antistatic polyurethane elastic fiber and material for producing the same

ABSTRACT

Inorganic salts are generated in the production process of metal salts, such as sulfonates, sulfates and phosphates. When such metal salts containing inorganic salts are added as an antistatic agent to a polymer for producing polyurethane fiber, the inorganic salts cause fiber breakage or pack choking in fiber extrusion process. In addition, such antistatic agents are highly hygroscopic and contain trace of water. When such an antistatic agent is added to the material for polymerizing polyurethane, the alcohol and water in the agent react with isocyanate to result in lowered degree of polymerization and generation of oligomer. Such polyurethane polymer is spun into fiber of low elongation and tenacity. The material for polyurethane elastic fibers of the present invention comprises a mixture of 5 to 95 weight percent of at least one of the above-mentioned antistatic agents and 95 to 5 weight percent of a isocyanate-free starting material for elastic fibers, and eliminates the above troubles.

TECHNICAL FIELD

The present invention relates to an antistatic polyurethane elasticfiber and the material for producing the same.

PRIOR ART

Japanese Patent Publication Laid-Open Hei 7-166426 describes an elasticyarn containing 0.1 to 5 weight percent of sulfonates having C₁₂₋₂₂hydrocarbon chain, of which surface is coated with a finish containingdimethyl siloxane.

Japanese Patent Publication Laid-Open Hei 1-90258 describes a processfor producing antistatic polyurethane foam by dissolving an organicsulfonate and phosphonium salt in a dope for producing polyurethane andby reacting the dope into polyurethane.

Inorganic salts are generated as a byproduct in the production processof sulfonates having hydrocarbon chain, sulfates having hydrocarbonchain and phosphates having hydrocarbon chain. Such metal saltscontaining the inorganic salts result in fiber breakage and pack chokingin fiber extrusion process when they are used in a polymer dope forfiber production, because the inorganic salts are insoluble in polymerdope. Therefore the above-mentioned sulfonates and others must bepurified with an organic solvent, such as alcohol, to eliminate theinorganic salts before used in the polymer dope. On the other hand, theabove-mentioned sulfonates and others are usually hygroscopic andcontain trace of water. Thus 1 or more weight percent of alcohol andwater remain in the above-mentioned sulfonates and others after they arepurified into 100% and treated in vacuum drying. Such sulfonates andothers containing alcohol and water lower the degree of polymerizationor generate oligomer when they are added in the polymerization processof polyurethane because of the reaction between the alcohol or water inthe metal salts and isocyanate. And such polyurethane is spun into fiberof lowered elongation and tenacity.

DISCLOSURE OF INVENTION

The object of the present invention is to provide a material whichcontains sulfonates and the like having hydrocarbon chain for producingantistatic polyurethane elastic fiber containing the sulfonates and thelike having hydrocarbon chain as an antistatic agent.

Another object of the present invention is to provide a materialcontaining minimum alcohol and water to minimize the inhibition ofpolyurethane formation due to the reaction between the alcohol or waterand isocyanate for the purpose of producing antistatic polyurethane.

Further object of the present invention is to provide a material, inwhich sulfonates and the like are contained as an antistatic agent andthe sulfonates and the like contain minimum inorganic salts, forproducing antistatic polyurethane elastic fiber.

Further object of the present invention is to provide antistaticpolyurethane elastic fiber having sufficient tenacity and elongation asan elastic fiber.

Further object and advantage of the present invention are clearlyillustrated in the following description.

First, the above object and advantage of the present invention areachieved by a material for producing antistatic polyurethane elasticfiber comprising a mixture of 5 to 95 parts by weight of at least onesalt selected from the group consisting of sulfonates having C₈₋₃₀hydrocarbon chain, sulfates having C₈₋₃₀ hydrocarbon chain andphosphates having C₈₋₅₀ hydrocarbon chain; and 95 to 5 parts by weight(based on 100 parts by weight of the total of the mixture) of a startingmaterial other than organic isocyanate for producing polyurethaneelastic fiber.

Secondly, the above object and advantage of the present invention areachieved by an antistatic polyurethane elastic fiber containing 0.1 to10 weight percent of the above-mentioned salts and 0.1 to 10 weightpercent of lubricants, and having a tenacity of 1 g/de or more and anelongation of 400% or more.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 illustrates the device for measuring the yarn tension in asimulated knitting operation.

PREFERRED EMBODIMENT OF INVENTION

The material referred to in the present invention is a material forproducing an antistatic polyurethane elastic fiber. The polyurethaneelastic fiber of the antistatic polyurethane elastic fiber is thepolyurethane fiber produced from the starting material comprisinglong-chain glycols such as polytetramethylene glycol and polyesterdiol,and short-chain bifunctional compounds such as 1,2-propylenediamine and1,4-butanediol. Such fiber can be produced by dissolving polyurethane inspinning solvent to prepare a dope and by spinning the dope in awell-known manner.

The salts applied as an antistatic agent to the material of the presentinvention are sulfonates having C₈₋₃₀ hydrocarbon chain, sulfates havingC₈₋₃₀ hydrocarbon chain and phosphates having C₈₋₅₀ hydrocarbon chain.Either one or more of those salts can be used for the material.

Preferable sulfonates having C₈₋₃₀ hydrocarbon chain are, for example,pottasium alkanesulfonate having 15.5 carbon atoms on the average,lithium alkanesulfonate, having 10.5 carbon atoms on the average, sodiumdodecylbenzenesulfonate, sodium dibutylnaphthalenesulfonate,tetrabutyl-phosphonium toluenesulfonate, trioctylmethylammoniumtoluenesulfonate, sodium polyoxyethylene lauryl ether propane sulfonate,potassium nonylphenyl ether propane sulfonate, sodium petroleumsulfonate and the like.

Preferable sulfates having C₈₋₃₀ hydrocarbon chain are, for example,sodium octyl sulfate, potassium stearyl sulfate, tetrabutylphosphoniumcetyl sulfate, sodium polyoxyethylene lauryl ether sulfate, potassiumpolyoxyethylene nonylphenyl ether sulfate, lithium castor oil sulfate,sodium sulfate methylricinoleate and the like.

Preferable phosphates having C₈₋₅₀ hydrocarbon chain are, for example,sodium mono- and dilauryl phosphate, potassium mono- and distearylphosphate, sodium mono- and dipolyoxyethylene lauryl ether phosphate,potassium mono- and dipolyoxyethylene nonylphenyl ether phosphate andsodium mono- and dibutyl phosphate.

The said antistatic component of the present invention must be free fromthe groups reactive with organic isocyanates. And metal salts arepreferable as the antistatic component for their antistatic effect.

According to the present invention, the polyurethane elastic fibercontains 0.1 to 10 weight percent, preferably 0.3 to 3 weight percent,of the said antistatic agent. The amount beyond the above range resultsin insufficient antistatic effect or lowered tenacity and elongation.

The amount of inorganic matter in the antistatic agent is preferably 0.5weight percent or less, more preferably 0.1 weight percent or less.Greater amount of the inorganic matter causes fiber breakage andspinning pack choking.

The said material of the present invention contains salts such as theabove-mentioned sulfonates and a starting material for producingpolyurethane elastic fiber other than organic duisocyanates. Thepreferable ratio of the former, the salts, is 5 to 95 parts by weightand that of the latter, the material, is 95 to 5 parts by weight basedon 100 parts by weight of their total.

The latter, the starting material for producing polyurethane elasticfiber includes, for example, long-chain glycols and short-chainbifunctional compounds for producing polyurethane, spinning solvent,lubricants, antioxidants, and ultraviolet-ray absorbers. Either one ormore of those materials can be used. Long-chain glycols, spinningsolvent, and lubricants are preferable among them.

The long-chain glycols for producing polyurethane include, for example,polytetramethylene glycol, polyesterdiol, polypropylene glycol andpolyethylene glycol. Among those compounds, polytetramethylene glycoland polyesterdiol are preferable.

The short-chain bifunctional compounds for producing polyurethaneinclude, for example, succinic acid, adipic acid, ethylene glycol,propylene glycol, 1,4-butanediol, hexanediol, hydrazine,1,2-propylene-diamine, 1,4-butylenediamine, 1,6-hexamethylenediamine,and m-xylylene-diamine.

The spinning solvent includes, for example, dimethylformamide,N,N′-dimethylacetamide, N,N,N′,N′-tetramethylurea, N-methylpyrrolidone,and dimethyl sulfoxide. Among those, N,N-dimethylformamide andN,N-dimethylacetamide are preferable.

The lubricants include, for example, metal salts of saturated higherfatty acid such as magnesium stearate, modified silicones such asamino-modified silicone, alkylether-modified silicone andpolyether-modified silicone, and higher fatty acid amide. Among those,modified silicone and bisamide such as ethylenebistearic acid amide arepreferable.

The antistatic polyurethane elastic fiber of the present invention canbe produced advantageously from the above material of the presentinvention. The water and alcohol contained in the above-mentionedmaterial of the present invention can be decreased to a very low levelbefore the material is mixed with organic diisocyanates through blendingthe material with a starting material for producing polyurethane elasticfiber other than organic diisocyanates and drying the mixture in awell-known manner such as drying under low-pressure. The preferableamount of each water and alcohol in the material of the presentinvention is 0.5 weight percent or less, more preferably 0.1 weightpercent or less.

The material of the present invention is processed into polyurethaneelastic fiber in a well-known process where the material of the presentinvention is treated in the same manner as that for an ordinary startingmaterial for producing polyurethane elastic fiber other than organicdiisocyanates.

The present invention provides an antistatic polyurethane elastic fibercontaining 0.1 to 10 weight percent of the above-mentioned salt as anantistatic agent and 0.1 to 10 weight percent of a lubricant, and havinga tenacity of 1 g/de or more and elongation of 400% or more.

The fiber of the present invention can be produced from the saidmaterial of the present invention without decrease of the degree ofpolymerization, generation of oligomer, lowered tenacity and elongationof resultant fiber and generation of deposit, owing to the low amount ofwater, alcohol and inorganic salt in the material. In addition, thefiber of the present invention has uniform antistaticity because theantistatic component being dispersed in the material prior to fiberproduction easily mixes into spinning dope and disperses homogeneously.

EXAMPLES

The present invention is specifically explained with the followingexamples.

Example 1

Mono- and dipolyoxyethylene lauryl ether phosphate was neutralized withan aqueous solution containing 50-% potassium hydroxide and made into apolytetramethylene glycol solution containing 50% of mono- anddipolyoxyethylene lauryl ether phosphate. The solution was heated up to130° C. and the water in the solution was evaporated at −700 mmHg toobtain polytetramethylene glycol solution of potassium mono- anddipolyoxy-ehtylene lauryl ether phosphate containing 200 ppm of waterand 0.05 weight percent of inorganic salt (hereinafter referred to asAdditive a).

Example 2

Crude sodium octyl sulfate containing sodium sulfate decahydrate wasdissolved in ethanol to precipitate sodium sulfate decahydrate andfiltered. The filtered solution was dried to obtain a powder containing0.05 weight percent of ethanol, 0.02 weight percent of water and 0.01weight percent of inorganic salt. Then the powder was made intoN,N-dimethyl acetoamide (DMAc) solution containing 10 weight percent ofthe powder (hereinafter referred to as Additive b).

Example 3

Crude dodecylbenzenesulfonic acid containing sulfuric acid wasneutralized with a mixture of sodium hydroxide and methanol toprecipitate sodium sulfate decahydrate and to obtain a methanolicsolution containing 70% of sodium dodecylbenzenesulfonate. Sixty sevenparts by weight of polyether-modified silicone (EO:PO=60:40, viscosity3000 cSt at 25° C.) was added to 47 parts by weight of the solution, andthe mixture was heated up to 130° C. to evaporate methanol at −700 mmHgand to obtain a solution containing 0.06 weight percent of water, 0.05weight percent of methanol and 0.01 weight percent of inorganic salt(herein-after referred to as Additive c).

Example 4

Crude sodium alkanesulfonate having 15.5 carbon atoms on the average andcontaining sodium sulfate decahydrate was dissolved in methanol toprecipitate sodium sulfate decahydrate and was filtered. After filteringthe solution, ethylenebisstearic acid amide was added to the solution to20 weight percent of the sodium alkanesulfonate having 15.5 carbon atomson the average. Then the solution was heated up to 130° C. and vacuumdried at −700 mmHg to obtain a solution containing 0.4 weight percent ofwater, 0.1 weight percent of methanol and 0.02 weight percent ofinorganic salt (hereinafter referred to as Additive d).

Example 5

The mixture of 98 parts by weight of polytetramethylene glycol of 1500number average molecular weight, 2 parts by weight of Additive a, and 33parts by weight of 4,4-diphenylmethane diisocyanate was reacted at 70°C., and then 266 parts by weight of N,N-dimethylacetamide was added todissolve the reacted mixture with cooling. After the solution was cooleddown to 5° C., a solution prepared by dissolving 5 parts by weight of1,2-diaminopropane in 184 parts by weight of N,N-dimethylacetamide, and10 parts by weight of Additive a were added to the solution. Thespinning dope prepared in the above procedure was fed to a spinnerethaving four fine holes, and extruded at 200 m/min into hot air in whichsolvent was evaporated. The extruded fiber was applied with 5 parts byweight of a 1 to 1 mixture of a dimethyl silicone having a viscosity of10 cSt and a mineral oil of 60 sec, and wound up into 40 denierthickness. The properties of the resultant fiber are shown in Table 1.

Example 6

The mixture of 100 parts by weight of polytetramethylene glycol of 2000number average molecular weight and 25 parts by weight of4,4-diphenylmethane diisocyanate was reacted at 70° C. Then 250 parts byweight of N,N-dimethyl acetoamide was added to the reaction mixture todissolve the mixture with cooling. After cooling down the solution at 5°C., a solution prepared by dissolving 3.7 parts by weight of1,2-diaminopropane in 183 parts by weight of N,N-dimethylacetamide and10 parts by weight of Additive b were added to the solution. Thespinning dope obtained in the above procedure was spun into fiber in thesame manner as in Example 5. The properties of the resultant fiber areshown in Table 1.

Example 7

A fiber was spun in the same manner as in Example 6 except that 2 partsby weight of Additive c was added instead of 10 parts by weight ofAdditive b. The properties of the resultant fiber are shown in Table 1.

Example 8

The mixture of 100 parts by weight of polymethylpentanediol adipate of2000 number average molecular weight, 9 parts by weight of1,4-butanediol, 37.5 parts by weight of 4,4-diphenylmethanediisocyanate, and 2 parts by weight of Additive d was reacted at 85° C.The resultant reaction product was taken out of the kneader, andextruded at 200° C. from four fine holes with an extruder at 200 m/min.The extruded fiber was applied with 5 parts by weight of a 1 to 1mixture of a dimethyl silicone having a viscosity of 10 cSt and amineral oil of 60 sec, and wound into 40 denier thickness. Theproperties of the resultant fiber are shown in Table 1.

Example 9

A fiber was spun in the same manner as in Example 8 except that theamount of Additive d was changed to 0.5 parts by weight. The propertiesof the resultant fiber are shown in Table 1.

Example 10

A fiber was spun in the same manner as in Example 6 except that 0.5parts by weight of Additive c was added instead of 10 parts by weight ofAdditive b. The properties of the resultant fiber are shown in Table 1.

Comparative Example 1

A fiber was spun in the same manner as in Example 7 except that acommercially available alkanesulfonate having 14.5 carbon atoms on theaverage (containing 4 weight percent of inorganic salt and 2 weightpercent of water) instead of Additive c. The pack pressure increasedwhen the dope was extruded from the spinneret, and the dope could beextruded only for 5 hours. The resultant elastic yarn had an elongationof 270% and a tenacity of 0.5 g/de, and was not used as elastic yarn.

Comparative Example 2

An elastic yarn was spun in the same manner as in Example 1 except thatno additives were added. The properties of the resultant fiber are shownin Table 1.

Knitting tension:

The testing mechanism of a yarn in knitting operation is shown inFIG. 1. A polyurethane yarn (2) unwound from a cheese (1) is driventhrough a compensator (3), rollers (4), knitting needles (5), a roller(7) attached to a U-gauge (6), and a speed meter (8), and connected to awinding roller (9). Yarn speed was controlled constant at a given speed(for example, 10 m/min or 100 m/min) with the speed meter (8), and ayarn was wound onto the winding roll. The variation of the yarn tensionwhile the winding operation was measured with the U-gauge (6) todetermine the friction (g) between the yarn and the knitting needles.

Static charge:

An electrometer (KS-525, Kasuga Electric Company) was placed 1 cm abovethe U-gauge, and the static charge on the driven yarn was detected.

Specific resistance:

The specific resistance was tested with a Fiber Tester (Type MR-2010,Dempa Ind. Co., Ltd.).

TABLE 1 Ex. Ex. Ex. Ex. Ex. Ex. Comp. Test No. 5 6 7 8 9 10 Ex. 2Knitting tension (g)  10 m/min 20 21 20 20 21 20 20 100 m/min 25 27 2325 25 24 25 Static charge (kv)  10 m/min 0.1 0.1 0.1 0.2 0.3 0.1 0.5 100m/min 0.2 0.2 0.1 0.3 0.3 0.2 2.0 Specific 2 × 10⁸ 3 × 10⁸ 1 × 10⁸ 4 ×10⁸ 5 × 10⁸ 2 × 10⁸ 4 × 10¹¹ resistance (Ω · cm) Tenacity (g/de) 2.3 2.62.4 2.3 2.0 2.4 2.3 Elongation (%) 590 620 610 560 570 610 580 Ex.:Example Comp. Ex.: Comparative Example

The material of the present invention enables to produce yarn havingsuperior properties (elongation of 400% or more and tenacity of 1 g/deor more), to =prevent static charge on elastic yarn in covering andbeaming process, and to decrease troubles such as yarn breakage.

1. A material for producing antistatic polyurethane elastic fiber, saidmaterial being the mixture (of which total is 100 parts by weight) of 5to 95 parts by weight of at least one salt selected from the groupconsisting of sulfonates having C₈₋₃₀ hydrocarbon chain, sulfates havingC₈₋₃₀ hydrocarbon chain and phosphates having C₈₋₅₀ hydrocarbon chain,and 95 to 5 parts by weight of a starting material for producingpolyurethane elastic fiber other than organic isocyanate.
 2. Thematerial in claim 1, wherein the starting material for producingpolyurethane elastic fiber comprising long-chain glycol for producingpolyurethane, spinning solvent, and lubricants.
 3. The material in claim2, wherein the long-chain glycol for producing polyurethane elasticfiber is polytetramethylene glycol or polyesterdiol.
 4. The material inclaim 2, wherein the spinning solvent is N,N-dimethyl-formamide orN,N-dimethylacetamide.
 5. The material in claim 1, wherein thelubricants are bisamides or modified silicones.
 6. An antistaticpolyurethane elastic fiber containing 0.1 to 10 weight percent of atleast one salt selected from the group consisting of sulfonates havingC₈₋₃₀ hydrocarbon chain, sulfates having C₈₋₃₀ hydrocarbon chain andphosphates having C₈₋₅₀ hydrocarbon chain (in which 0.5 weight percentor less of inorganic salts to the weight of the metal salts arecontained), and 0.1 to 10 weight percent of the lubricants, and having atenacity of 1 g/de or more and an elongation of 400% or more.